As is well know, an image forming apparatus, such as a copier, a printer, a facsimile machine, a multifunctional machine combining these devices, etc., utilizes a printing head having one or more liquid droplet ejection heads to eject liquid drops, such as ink, etc. Alternatively, an image forming apparatus employs an electrophotographic system and renders a latent image visible by supplying developer thereto. Specifically, the former liquid droplet ejection system forms an image by ejecting and adhering or impregnating liquid drops onto a recording medium, such as a recording sheet, etc., while conveying the recording medium.
Further, it is important for an image forming apparatus equipped with a liquid droplet ejection device to maintain and apply negative pressure to ink in a liquid droplet ejection head (i.e., pressure applied to ink needs to be kept negative in a liquid droplet ejection head) for the purpose of stabilizing ink ejection from the liquid droplet ejection head. For this reason, a negative pressure generator is generally included in an ink supply system that supplies ink to the liquid droplet ejection head. Thus, the ink is supplied to the liquid droplet ejection head under the negative pressure being applied by the negative pressure applicator.
By contrast, the latter image forming apparatus employing an electrophotographic process generally applies charging, exposing, developing, and transferring processes to a photoconductor serving as an image bearer, thereby forming an image thereon. A latent image formed on the photoconductor is then rendered visible by a developing device and is transferred onto a recording medium as a visual toner image.
Hence, in both of the liquid droplet ejection device and the electrophotographic system, a copy is obtained by forming an image on the recording medium. A recording sheet as one type of recording media is either conveyed from a sheet feeding cassette or a manual sheet feeding tray other than the sheet feeding cassette. A sheet feeding cassette system capable of feeding multiple recording sheets stacked in a sheet feeding cassette therefrom one by one is known, in which, for example, a mounting plate is provided in a body of the sheet feeding cassette to displace a leading end of the recording sheet toward an feeding roller, so that the feeding roller can feed a top most recording sheet contacting thereto among those stacked on the mounting plate.
Further, it is demanded these days that replacement of the above-described sheet feeding cassette and removal of printed sheets can be performed from the front of an apparatus body to improve usability. To fulfill such demand, it is attempted that a manual sheet feeding tray and a sheet ejection tray are provided above a detachably attached section for the sheet feeding cassette, as disclosed in Japanese Patent Application Publication No. 2006-16188 (JP-2006-16188-A). Specifically, it is disclosed in JP-2006-16188-A that recording sheets stacked on a sheet feeding cassette inserted from a front side of an ink jet printing system equipped with a liquid droplet ejection device are fed one by one from a rear side of the sheet feeding cassette, are conveyed by a conveyance belt to receive printing while facing a printing unit, and are then ejected onto a sheet ejection tray. Also disclosed in JP-2006-16188-A is an inversion conveyance path connected to a conveyance path, which is connected to the printing unit, at the rear side in the sheet feeding cassette to invert and convey the recording sheet toward the printing unit for printing on another side.
By arranging structural members of such operation objectives on the front side surface of the apparatus as shown in JP-2006-16188-A, operations to be executed at the rear side of the apparatus and hardly reachable by hand can be omitted. However, new problems arise. Specifically, since the inversion conveyance path protrudes outside the apparatus body equipped with the sheet feeding cassette, the footprint of the apparatus as a whole increases.
Further, since an feeding position where the recording sheet is fed from a sheet feeding cassette is at a rear side in the sheet feeding cassette installed in the apparatus (i.e., an opposite side to the front side of the apparatus), removal of a jammed sheet needs to be performed at the rear side, thereby degrading usability in comparison with that performed at the front side. Further, the recording sheet fed from the sheet feeding cassette and then subjected to a printing process is ejected onto the sheet ejection tray as is. However, since an image surface of the printing sheet ejected on the sheet ejection faces upward and subsequent recording sheets are similarly stacked thereon, a printing order of the recording sheets stacked on the sheet ejection tray is inconsistent with a page number order of those as a result.